Sponge iron is an important iron and steel feedstock. Sponge iron is a metallic iron consisting of powder or porous structure. Commercial production of the sponge iron can be generally divided into two types; the coal and the gas processes. Reduction of iron ore can be achieved by using either carbon bearing material, such as non-coking coal or a suitable reducing gas in the form of reformed natural gas. The processes employing coal are known as solid-reluctant of coal-based processes while those employing reducing gases are known as gas-based processes. Sponge iron produced by gas-based process is normally hot briquette and hence it is also known as Briquette Iron (HBI). Sponge iron, also called direct reduced iron, is the product created when iron ore is reduced to metallic iron, usually with carbon (charcoal), at temperatures below melting point of iron. Currently, problem faced by manufacturers in producing the sponge iron is that the carbon content in the sponge iron is difficult to be altered or to be produced in desirable carbon content. This situation occurs in both the coal and gas processes. In the gas based process, iron oxide source is introduced in a bulky amount into a furnace for a reduction process to produce sponge iron. The sponge iron produced at the end of the reduction process generally contains high carbon content of 4-6%. In order to reduce the carbon content, it is subjected to a subsequent process of controlled oxidation wherein, the carbon content is further reduced. This further increases cost of the production of the sponge iron.
Conventional sponge iron possesses high carbon content as a result of the carbon is inherently dissolvable in the metallic iron during the production. 4-6% carbon is generally present in the conventional sponge iron and manufacturers are finding all the way to reduce its carbon content. Effort of carbon removal is carry out all the time and one of it is the increase of oxygen partial pressure in the gas-process. However, not many breakthrough of technology was obtained for the removal of carbon effectively and efficiently.
Therefore, there is a need for a process for producing sponge iron which allows the alteration of carbon content that is desired in the sponge iron and also to have a process that reduces carbon content effectively and efficiently.